High-performance braking - Aeronautical example

The first airplanes had no brakes. They didn't need them; their weight and take-off speed were low enough. Then, as engines became more powerful, planes got bigger and faster. Their wheels were then fitted with brakes extrapolated from those used on automobiles, i.e. drum brakes with independent control for each side, which also enabled them to take turns at low speed. The propellers of piston engines, or even later turboprop engines, were equipped with variable pitch and even pitch reversal, making them easy to slow down. With jet engines, brakes became critical, as they were virtually the only truly effective means of slowing down.

Today's disc brakes are capable of absorbing high levels of energy with reasonable mass, and are made of materials that can withstand increasingly high temperatures at the end of braking.

At the same time, the torque capacity of the brakes required automatic assistance to prevent wheel lock-up and ensure high braking efficiency. This was made possible, in particular, by the introduction of analog, then digital, electronic control units. The latter also offer the possibility of performing other complementary braking functions, such as front landing gear steerability, and of course monitoring and maintenance aids.

This article focuses on wheel brakes, which are the main means of slowing down the vehicle. They differ from those found on other vehicles in their energy capacity (up to 140 MJ per wheel), initial braking speed (360 km/h) and maximum instantaneous power developed (over 10,000 kW). Of course, the weight has to be as low as possible, the materials used highly efficient, such as carbon/carbon composites, and the end-of-braking temperatures very high, around 1,500°C in some cases. The control system, also specific to aircraft, is briefly described.

This study is by no means exhaustive or in-depth, if only because techniques are constantly evolving and each manufacturer has its own.

Most of the documentation refers to Messier-Bugatti brakes; where this is not the case, the name of the manufacturer is given.